***This article was written by Angela Mason Foster, Extension Master Gardener℠ volunteer of Beaufort County ***
Few sights in nature rival the brilliance of fall foliage. A row of maples glowing scarlet, a canopy of golden hickories, or the purple shimmer of sweet gum leaves against a crisp blue sky can make even the most ordinary roadside feel magical. In eastern North Carolina, we may not have the towering mountains of the Blue Ridge, but we still enjoy our own displays of color each October and November. But what exactly causes leaves to change color? The answer lies in science—specifically pigments, weather, and plant physiology.Green to Gold: Chlorophyll’s Disappearing Act
During spring and summer, leaves are green because of chlorophyll, the pigment responsible for capturing sunlight and fueling photosynthesis. Plants work hard all summer, producing sugars that support growth, flowering, and fruiting. But as the days shorten and temperatures drop, trees receive signals to prepare for winter. Chlorophyll production slows, then stops altogether, and the green color fades.When chlorophyll breaks down, the pigments that have been present all along—carotenoids—are revealed. These are the same pigments that give carrots their orange color and corn its yellow. In autumn, they create the golden glow in hickories, the buttery yellows in tulip poplars, and the warm tones in ash and birch.The Reds and Purples: A Seasonal Surprise
Unlike carotenoids, which are always in the leaf, anthocyanins—the pigments responsible for red, crimson, and purple hues—are produced in the fall. They form when sugars become trapped in leaves after nights grow longer and cooler. In maples, dogwoods, sumacs, and sweet gums, anthocyanins act almost like sunscreen, protecting leaves from light damage and helping trees recover nutrients before the leaves drop.That’s why a maple tree might blaze crimson one year and look more orange the next: the intensity of red depends on the balance of sugars, sunlight, and temperature in a given season. Bright, sunny days followed by crisp, cool nights produce the most brilliant reds and purples.Weather Matters
Weather patterns throughout the growing season also influence fall color. Adequate rainfall in spring and summer helps trees stay healthy, while drought can dull colors or cause leaves to drop early. A warm, wet fall may delay color change, while an early frost can mute the reds and shorten the season.Here in coastal and eastern North Carolina, we see less dramatic displays than the mountains, partly because of milder temperatures and partly because our forests are dominated by evergreens like pines. Still, sweet gum, dogwood, red maple, black gum, and sassafras all contribute striking patches of color, especially along rivers and woodlands. Even the brilliant red of poison ivy winding up a tree trunk adds to the seasonal palette—though admired only from a distance!Why Do Leaves Fall at All?
Color change is only part of the process. As chlorophyll fades and other pigments shine through, trees also form a layer of specialized cells at the base of each leaf stem. This “abscission layer” gradually seals off the leaf from the rest of the tree, allowing it to drop without leaving an open wound. It’s a survival strategy: by shedding leaves, deciduous trees conserve water and energy during the winter when frozen soil makes it difficult to take up moisture.Appreciating the Science and the Beauty
Understanding the pigments behind fall color doesn’t make it any less magical—it deepens our appreciation. The glow of a maple is no less beautiful once you know anthocyanins are at work. The golden shimmer of hickory leaves is more meaningful when you realize it’s carotenoids stepping into the spotlight. Science gives us a vocabulary for the beauty we see, and nature provides endless opportunities for awe.Gardening with Fall Color in Mind
Home gardeners can harness some of this seasonal beauty by planting trees and shrubs known for their autumn displays. In addition to native dogwoods, maples, and sweet gums, consider black gum (Nyssa sylvatica) for its deep red leaves, or oakleaf hydrangea for its rich burgundy foliage. Even smaller shrubs like blueberries provide both edible fruit and fiery fall color. Planting with autumn in mind ensures that your garden delights you long after summer flowers have faded.As you walk, drive, or simply look out your window this fall, take a moment to appreciate the science behind the spectacle. Every golden hickory leaf and scarlet maple is a reminder that change can be beautiful, that endings prepare the way for renewal, and that even the humblest leaf carries the chemistry of wonder.
So whether you’re headed west to see the mountain slopes painted in color, or simply admiring a dogwood in your own backyard, remember this: fall color is both art and science, a seasonal gift wrapped in red, gold, and purple.Suggested Reading
- Tim Barnes, Trees of the Carolinas – an accessible guide to identifying local trees in every season
- Peter Wohlleben, The Hidden Life of Trees – an exploration of the science and wonder of forests
